Clutch control with cooling means therefor



y 1958 v. w. PETERSON ETAL 2,833,385

CLUTCH CQNTROL WITH COOLING MEANS THEREFOR v Filed May 11, 1953INVENTOR5 v ZATTOENE Y CLUTCH CONTROL WITH COOLING MEANS THEREFORVictonW. Peterson and Marshall H. Thomas, Indianapohs Ind., assignors toGeneral Motors Corporation, Detroit, Mich a corporation of DelawareApplication May 11, 1953, Serial No. 354,334

2 Claims. ((il. 192-113) fluid to the clutch to engage the same, todisengage the same, and to cool the same during the periods of slipwhile the clutch is being engaged or disengaged.

A further object of the invention is to provide a hydraulic clutch witha control system wherein the clutch is engaged by relatively lighthydraulic pressure to avoid abrupt clutching, wherein the clutchingpressure is increased by centrifugal force to carry full load torque,and wherein the clutch is disengaged by relatively high hydraulicpressure to provide rapid declutching.

Further objects and advantages of the present invention will beapparent. from the following; description, reference being had to theaccompanying drawing wherein a preferred form of the present inventionis clearly shown.- I

The drawingis a somewhat schematic representation of a known type of.clutch incorporating the control system of the invention.

The invention is particularly useful in aircraft power systems of thetype employing, contrarotati-ng. propellers driven through a pair of.clutches by a pair of gas tur bine engines. References may be had to thecopending application of Peterson and Schnepel S. N. 174,052 filed .iuly15, 1950- for further details of such a system and for a specificstructural disclosure of the clutches therefor.

The hydraulic clutch: it) includes a driving. shaft 12 which may bedriven from a gas turbine engine or other suitable source of power and adriven drum 14 which may supply power toan aircraft. propeller or othersuitable driven member. terleaved' disks l6- and 18 respectively securedfor axial movement and: rotation to the driving shaft 12 and the drivendrum 14 by internal and external splines 20 and 22 formed thereon. Anannular member 24 is secured: for axial movement on the driving shaft12' and forms. a pair of' annular hydraulic actuating chambers 26 and 28with a disk-like flange 30 of the driving shaft 12. The. clutch isengaged by supplying hydraulic fluid. under predetermined pressurethrough radial passages 32 tothe: clutch engagement chamber 26, therebyforcing the clutch-disks together and against the disklike abutment 34on the driving shaft. The clutch is disengaged by supplying hydraulicfluid under predetermined pressure through radial passages 36 to thedisengagement chamber 28, thereby releasing the" pressure on the clutchdisks. The clutch disks are cooled and lubricated during the periods ofengagement and disengagement by supplying hydraulic fluid underpredetermined pressure through the radial passages 38*, which fluidcollects in the sump 49 0f the gear pump-- 42 of the hydraulic system:after fiewi-ng between the clutch disk-s. A plurality of slip tubes 46and 48 supply The clutch employs inv Patented May ,6, 1958 the clutchwith engagement, disengagement and cooling fluids respectively.

A cross passage 47 connects the disengagement and coolant passages 36and 38 to supply hydraulic fluid at insignificant pressure to thedisengagement chamber 28 during the engaging period of clutch operationso that the hydrostatic presures due to centrifugal action in theengagement and disengagement chambers 26 and 28 will be substantiallybalanced, thereby preventing too abrupt clutching. The disengagementchamber 28. is provided with a bleed-off orifice 49 and with a bleedoffconduit 50 which is controlled by a spring-biased speed responsive valve52. The orifice 49 will partially empty the hydraulic fluid in thedisengagement chamber 28 at intermediate speeds of the shaft 12 whilethe clutch is being engaged. The speed responsive valve 52 is set toopen at substantialor near operating speeds of the shaft 12 and empty orfurther empty the hydraulic fluid in the disengagement chamber 23. Thehydraulic pressure due to centrifugal action in the engagement chamber26 is therefore not balanced at the higher speeds by hydrostaticpressure in the chamber 28 and thus augments the static pressure in theengagement chamber 26 from the pump 42 to enable the clutch disks totransmit high loads Without slip. The disengagement chamber 28 issupplied with hydraulic fiuid at a higher pressure during thedisengagement period of the clutch than that supplied to the engagementchamber 26 during the engagement period of the clutch. The engagement ofthe clutch is thus relatively slow with respect to disengagement as anabrupt clutching to the load might be destructive while a rapiddeclutching from the load-is desirable.

A clutch actuating flow valve 60 supplies engagement fluid, preferablyoil, at reduced pressure to the clutch through a conduit 62 when thedouble-spool valve piston 64 is in the solid line or right-hand positionEV in the valve cylinder 65. The outlet manifold 66 of the gear pump 42delivers the hydraulic fluid to the clutch actuating flow valve 60through a conduit 68, a spooltype pressure regulating reduction valve70, and a conduit 72. The pressure reduction valve 70 includes acylinder 74 and a spool valve piston 76 slidable therein. The left faceof the valve piston 76 is subjected to the outlet pressure in theconduit 72 by a groove 77 while the right face of the spool is subjectedto atmospheric pressure through a vent 7 3 and to resilient pressurefrom a spring 80; the spring pressure being suitably chosen so that thepressure in the conduit 72 is maintained at a fixed value substantiallyless than the system or pump pressure in the conduit 68.

The clutch actuating flow valve 60 also supplies disengagement oil tothe clutch. The disengagement oil is supplied at full system pressurethrough the conduit 82 from the conduit 84 when the double-spool valvepiston 64 is in the dotted line or left-hand position DV'. The clutchdisengagement chamber 28 is vented to the sump 40 through a groove 86 inthe cylinder 65 when the double-spool valve piston 64 is in the EVposition and the engagement chamber 26 is vented through a groove 83when the piston is in the DV position. Grooves 87 and 89 supply oil fromthe conduits 84 and 72 to the annular chambers formed by the cylinder 65and piston 64 in either EV or DV position.

A clutch coolant valve 90 supplies cooling and lubricating oil to theclutch disks through a conduit 92 at pump or system pressure from theconduit 66 when the single-spool valve piston 94 is in the solid line orrighthand EV position in the valve cylinder 95. The spool valve piston94 cuts off the flow of coolant to conduit 92 when in the dotted line orleft-hand VV position and is so biased by a spring 96.

The spool 64 of the clutch actuating flow valve 60 is operated by adouble-acting servomotor 100 which has a cylinder 101 and a piston 102slidable therein. The piston 102 is moved to the solid line orright-hand EV position when the operating lever 104 and rotary plug 105of a control valve 110 are placed in the solid line or E position totransmit fluid from the conduit 66 through the conduits 112 and 114 topressurize the servomotor chamber 116 and the operating lever 118 androtary plug 119 of a control valve 120 are placed in the solid line or Vposition to vent the servomotor chamber 122 to the sump 40 through aconduit 124 and an outlet126 in the cylinder 127 of the valve 120. Thepiston 102is moved to the dotted line or left-hand DV position byplacing the operating lever 104 of the control valve 110 in the dottedline or V position to vent the servomotor chamber 116 to the sump 40through the outlet 128 in the cylinder 129 of the control valve 110 andby placing the control lever 118 of the control valve 120 in the dottedline or D position to pressurize the servomotor chamber 122.

The servomotor 100 and the clutch actuating valve 60 are engageablylinked together by a push plate 130 that is secured to the servomotorpiston 102 to engage a flange 132 on the valve stem 134 of the clutchactuating valve 64 to engage the clutch when moved to the EV positionand to engage a flange 136 to disengage the clutch when moved to the DVposition. A spring-biased detent 138 cooperates with the annular notches139 and 140 on the valve stem to retain the same in the EV and DVpositions. The push plate 130 is movable from the EV to the VV positionwithout effecting movement of the valve stem 134 because of the spacingbetween the stem flanges 132 and 136. I

The coolant flow valve 90 is also engageably linked to the push plate130 of the servomotor 100, an annular flange 142 on the stem 144 of thecoolant valve being engageable with the push plate 130 between the EVand VV positions. The coolant valve stem 144 is also engageably linkedwith the piston 146 of a dashpot servomotor 150 between the EV and VVpositions. The piston 146 and cylinder 148 of the servomotor 150 form achamber 152 which connects by conduits 153 and 154 to the control valve110 through a metering orifice or bleed 156 and the conduit 112. Thechamber 152 also communicates with an accumulator 160 through a conduit162 and an accumulator control valve 170. The spool valve piston 172 ofthe accumulator control valve 170 is slidable in the cylinder 173 and issecured to the stem 134. The accumulator control valve 170 places thechamber 176 of the accumulator 160 in communication with the systempressure conduit 66 through the conduits 162 and 178 when the stem 134is in the EVposition; and cuts ofi this communication to place theaccumulator chamber 176 incommunication with the dashpot servomotorchamber 152 and the bleed 156 through the conduits 162, 153, and 154when the stem 134 is in the DV position. The accumulator 160 includes apiston 180 which is moved upwardly in a cylinder 181 against a spring182 when the chamber 176 is charged with system pressure when theaccumulator spool valve 172 is in the EV position, the spring 182serving to empty the chamber 176 to the conduits 153 and 154 when theaccumulator.

spool valve 172 is in the DV position.

The foregoing description covers the essential elements of a singleclutch and its control system and it should be understood that the gearpump 42 may be utilized to supply fluid to another clutch through asimilar control system through a branch conduit 184. It should also berealized that the control valves 110 and 120 may be manually operatedindependently of each other or coordinated to a single control through aSuitable linkage,

(ill

the supervision Engaging phase-cooling oil 011" The control valve isplaced in the E position thereby charging the chamber 116 of theservomotor 100, and the control valve is placed in the V positionthereby venting the chamber 122 of the servomotor 100 to the sump 40.The control valve 110 also commences to charge the chamber 152 of thedashpot servomotor 150 and the chamber 176 of the accumulator 160 at areduced rate through the bleed 156 and the accumulator control valve170. The servomotor push plate moves from the DV position to the EVposition thereby moving the coolant flow valve 90 from the VV positionto the EV position and the accumulator control valve 170 and clutchactuating valve 60 from the DV position to the EV position. The clutchactuating valve 60 supplies the engagement side of the clutch with oilunder reduced pressure and vents the disengagement side of the clutch tothe sump. The clutch coolant valve 90 supplies the clutch disks withcoolant oil at full system pressure. The I control valve 110 continuesto charge the dashpot servomotor and the accumulator control valve 170continues to charge the accumulator but from the conduit 178 rather thanthe bleed 156. The clutch is thus engaged.

Full engagement phase-cooling oil "off With the clutch brought up tospeed and its engagement complete, the control valve 110 is placed inthe V position thereby venting the chamber 116 of the servomotor 100 andthe chamber 152 of the dashpot servomotor 150. The coolant valve spring96 thereupon moves the coolant valve stem 144 from the EV to the VVposition, cutting off the flow of coolant to the clutch, being damped inthis movement by the restricted discharge of the oil in the dashpotservometer chamber 152 through the bleed 156. The push plate 130 of theservomotor 100 is likewise moved by the spring 96 from the EV positionto the VV position, but this movement does notaflfect the position ofthe clutch actuating valve 60 and accumulator control valve which remainin the EV position. The cooling oil is thus shut off while the clutch isengaged.

Disengagement phase-cooling oil momentarily "on" The control valve 120is placed in the D position to charge the chamber 122 of the servometer100. The servometer push plate 130 thereupon moves from the VV positionto the DV position placing the clutch actuating valve 60 and theaccumulator control valve 17 0 in the DV position. The clutch actuatingvalve 60 vents the engagement side of the clutch and commences thefilling of the disengagement side of the clutch with oil under systempressure (the disengagement side of the clutch having been graduallyemptied during the full engagement phase by the orifice 49 and the speedresponsive valve 52). The accumulator control valve 170 concurrentlyplaces the charged chamber 176 of the accumulator 160 in communicationwith the chamber 152 of the dashpot servomotor 150 and cuts off itscommunication with the system pressure supply conduit 178. Theaccumulator spring 182 (which is considerably heavier than the coolantvalve spring 96) thereupon moves the accumulator piston to dischargesome of the content of the large accumulator chamber 176 into 7 thesmaller dashpot servomotor chamber 152, forcing the coolant valve 90from the VV position to the EV position, thereby delivering cooling oilto the clutch at system pressure. The disengagement side of the clutchis now filled and the clutch is rapidly disengaged by the full systempressure, the flow of cooling oil aiding in separation of the clutchdisks. The oil in the dashpot servomotor chamber 152 and the remainingoil in the accumulator chamber 176 slowly discharges to the sump 40through the bleed 156 and control valve 110 under the influence of theaccumulator spring 182 and the coolant valve spring 96 whereupon thecoolant valve 90 moves from the EV to the VV' position cutting ofl theflow of cooling oil to the clutch. The clutch is thus disengaged and thecooling oil shut ofi.

While the preferred embodiment of the invention has been described fullyin order to explain the principles of the invention, it is to beunderstood that modifications in structure may be made by the exerciseof skill in the art within the scope of the invention, which is not tobe regarded as limited by the detailed description of the preferredembodiment.

We claim:

1. A clutching system comprising, in combination, a driving shaft, adriven shaft, a hydraulically operated clutch for coupling the drivingshaft to the driven shaft, means for supplying engaging and disengagingfluid to the clutch including a first valve, means for supplying coolingfluid to the clutch including a second valve, a first hydraulic motorfor operating the first valve to engage and disengage the clutch and foropening the second valve to supply cooling fluid to the clutch while itis being engaged, means for terminating the supply of cooling fluid tothe clutch by closing the second valve after the clutch is fullyengaged, and means for momentarily reopening the second valve to supplycooling fluid to the clutch while it is being disengaged including asecond hydraulic motor.

2. A clutching system comprising, in combination, a driving shaft, adriven shaft, a hydraulically operated clutch for coupling a drivingshaft to the driven shaft,

means for supplying engaging and disengaging fluid to the clutchincluding a first valve, means for supplying cooling fluid to the clutchincluding a second valve, a first hydraulic motor for operating thefirst valve to engage and disengage the clutch and for opening thesecond valve to supply cooling fluid to the clutch while it is beingengaged, means for terminating the supply of cooling fluid to the clutchby closing the second valve after the clutch is fully engaged; and meansfor momentarily reopening the second valve to supply cooling fluid tothe clutch while it is being disengaged including a second hydraulicmotor, an accumulator for charging the second hydraulic motor, a thirdvalve operable with the first valve to connect the accumulator and thesecond hydraulic motor, and a bleed for slowly releasing the charge ofthe accumulator and the second hydraulic motor.

References Cited in the file of this patent UNITED STATES PATENTS847,834 Sears et al Mar. 19, 1907 1,249,736 Frink Dec. 11, 1917 2,386,220 Lawler et a1 Oct. 9, 1945 7 2,437,430 Lawrence Mar. 9, 19482,498,123 Hobbs Feb. 21, 1950 2,642,844 Flinn June 23, 1953 2,658,596Archambault Nov. 10, 1953 2,690,248 McDowall Sept. 28, 1954 2,736,412Livezey Feb. 28, 1956 FOREIGN PATENTS 509,277 Great Britain July 13,1939 150,301 Great Britain Oct. 7, 1920

